GB2042300A - Short-range doppler radar system - Google Patents
Short-range doppler radar system Download PDFInfo
- Publication number
- GB2042300A GB2042300A GB8002057A GB8002057A GB2042300A GB 2042300 A GB2042300 A GB 2042300A GB 8002057 A GB8002057 A GB 8002057A GB 8002057 A GB8002057 A GB 8002057A GB 2042300 A GB2042300 A GB 2042300A
- Authority
- GB
- United Kingdom
- Prior art keywords
- frequency
- radar system
- signal
- short
- doppler radar
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000005670 electromagnetic radiation Effects 0.000 claims description 7
- 239000000758 substrate Substances 0.000 claims description 5
- 230000008878 coupling Effects 0.000 claims description 3
- 238000010168 coupling process Methods 0.000 claims description 3
- 238000005859 coupling reaction Methods 0.000 claims description 3
- 239000002184 metal Substances 0.000 claims description 3
- 239000000306 component Substances 0.000 description 17
- 230000005540 biological transmission Effects 0.000 description 11
- 230000010355 oscillation Effects 0.000 description 10
- 230000035945 sensitivity Effects 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/88—Radar or analogous systems specially adapted for specific applications
- G01S13/91—Radar or analogous systems specially adapted for specific applications for traffic control
- G01S13/92—Radar or analogous systems specially adapted for specific applications for traffic control for velocity measurement
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/03—Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver
- G01S7/032—Constructional details for solid-state radar subsystems
Landscapes
- Engineering & Computer Science (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Physics & Mathematics (AREA)
- Computer Networks & Wireless Communication (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Radar Systems Or Details Thereof (AREA)
Description
1 GB 2 042 300 A 1
SPECIFICATION
Short-range Doppler radar system The present invention relates to a short-range 70 Doppler radar system.
A Doppler radar system measures the velocity of a motor vehicle or any other moving object by radiat ing waves, e.g. microwaves, and detecting the Dop- pler shift in frequency of the waves which are reflected. If a microwave Doppler radar system is used for measuring the speed of a motor vehicle, the transmission power needs to be very low (1 to 10 jM or less) to prevent interference with, for example, other radio equipment. However, the receiving sensitivity needs to be as high as possible in order to achieve maximum accuracy.
A microwave Doppler radar system detects the Doppler frequency shift of reflected waves received by mixing a signal at the frequency of the received waves with a signal of the same frequency as the transmitted waves in a mixing circuit, and detecting the difference between the two frequencies. In order to make the radar system small in size (for use, for example, in a motor vehicle), a transmitter/receiver for the microwaves is constructed from an integrated circuit, and a mixer diode is used to form the mixing circuit.
In order to operate the mixer diode with a high sensitivity, it is necessary to apply a driving power of 95 approximately 1 mW. To achieve this, a balanced mixer, for example may be employed to reduce the microwave leakage power. However such an arrangement has the disadvantage that, when the two diodes which together form the balanced mixer, 100 degrade unequally in the course of time, the transmission power varies significantly.
According to the present invention there is provided a short range Doppler radar system compris- ing:
an oscillator which generates a first signal at a first frequency; a frequency multiplier device driven by said first signal which generates a second signal, said second signal having components which are harmonies of said first frequency; a filter which selects one of said components; an antenna which radiates electromagnetic radiation corresponding to said selected component externally of the radar system, receives reflected electromagnetic radiation, produces a third signal corresponding to said reflected electromagnetic radiation, and applies the third signal to the frequency multiplier; and a circuit for taking out a low frequency component from the frequency multiplier.
Such a Doppler radar system may be used to produce a system, using microwaves, with a low transmission power and a high receiving sensitivity. The transmission power is stable, even when the characteristics of a mixer diode or other circuit elements degrade in the course of time.
Preferably the frequency multiplier device is formed from a mixer diode or a Gunn oscillator device. A plate including an integrated circuit, may be installed inside a metal package, and a window is then provided in a part of the package, to which a horn antenna is coupled. The integrated circuit includes circuit elements such as the mixer diode and connection lines for applying the output of the oscillator to the mixer diode and for obtaining the fourth signal which is an output from the mixer diode.
Although the mixer diode, which forms the frequency multiplier device, is driven by a high power as is necessary for satisfactory operation, the power of the electromagnetic radiation that is radiated by the system can be reduced in comparison with the driving power of the mixer because a higher har- monic of a fundamental frequency may be selected by the filter and then radiated.
Embodiments of the present invention will now be described in detail, by way of example, with reference to the accompanying drawings, wherein:Figure 1 is a perspective view showing the construction of a first embodiment of a short-range Doppler radar system, Figure 2 is a constructional view of a second embodiment of a short-range Doppler radar system.
Referring first to Fig. 1, a package 1 has a metal wall in which a dielectric substrate 4, forming an integrated circuit, is installed, the wall being partially broken away in the figure in order to display the interior of the package 1.
An oscillator generating a signal at a fundamental frequency is formed by a Gunn diode 2 which is disposed within the package 1, and a bias circuit which consists of a DC power supply DC, a connector 9 and a strip line 5 formed on the substrate 4. The three components of the bias circuit are connected in series in order to apply to the Gunn diode a bias voltage necessary for its oscillation. The fundamental frequency f,, of the oscillation signal of the Gunn diode 2 is determined by the strip line 5 and a half wavelength resonator formed by a U shaped strip line 6. The power of the fundamental frequency oscillation signal is applied to a mixer diode 11 via a strip line 10.
Thus a signal is passed from the line 5 to the line 6, which has a length equal to one half wavelength of the fundamental frequencyfo, so that the line 6 resonates at that frequency. The resonant signal in the line 6 is then passed to the line 10 by resonance.
Hence only a signal having the desired frequency fo is passed from line 5 to line 10.
A low-pass filter bias circuit 7 and an antireflection terminating circuit 8 for the fundamental frequency oscillation signal prevent higher harmonic components of the signal and the fundamental frequency component itself from causing interference on the DC bias side of the circuit.
The mixer diode 11 functions as a frequency multiplier device, and when driven by the fundamental frequency oscillation signal f., it generates a harmonic signal having frequency components which are integral multiples (n, known as the order of the harmonic) of the fundamental frequency fo. In general, the power of the harmonic signal is reduced as the order of the harmonic increases.
2 GB 2 042 300 A 2 A part of the wall of the package 1 and a conductor attached to the rear surface of the substrate 4, corresponding to the position of the mixer diode 11, are removed as indicated by a dotted line 13, thereby to form a dielectric window. A rectangular waveguide 14, having a section indicated by the dotted line 13, is coupled to the dielectric window. A strap 12 short-circuits one terminal of the mixer diode 11 for the fundamental frequency oscillation signal, and straps 15 and 16 short-circuit both terminals of the mixer diode 11 to the conductor on the rear surface of the substrate 4 at the harmonic frequency (n -f. where n is integral) that is to be transmitted, which is generated by the mixer diode 11. The mixer diode is short circuited by straps 12, 15 and 16 for higher harmonics components. The driving signal is not short circuited. A strap 17 matches the input impedance of the mixer diode 11 to the fundamental frequency oscillation signal. The output waveguide 14 cuts off frequencies lower than the required transmission frequency n - f. and operates as a high-pass filter. The window 13 is selectively matched to the required transmitting frequency n -foandattenuates harmonics of a higher order. Thus, the output waveguide 14 transmits a signal with the required transmission frequency n - f. and radiates microwaves of lower power externally of the system through a horn antenna 23. The radiated microwaves may be reflected by a reflector, such as a road surface, moving relative to a vehicle carrying the radar system and undergo a Doppler frequency shift Af so that they have a frequency (n -f.+ Af). The reflected signal is applied to the mixer diode 11 via the horn antenna 23 and the waveguide 14.
The reflected signal from the reflector has been subjected to a Doppler shift in frequency, and the frequency difference Af between the transmitted and the reflected signals, which is proportional to the velocity of the microwave radar system relative to the reflector is detected from the mixer diode 11. The 105 received signal is applied to a load resistor 21 from an output signal terminal 20 by means of a direct current return circuit 18 and a strip line 19 and is detected as a Doppler signal.
The line 19 is earthed by strap 12 for high fre- 110 quency components, low frequency components not being earthed. Hence, the circuit formed by strap 12, line 19, terminal 20 and load resistor 21 takes out a low frequency component from the frequency mul- tiplier.
The frequency multiplier formed by the mixer diode 11 produces frequency components a f, t b f2, where a and b are integral, when two signals having frequencies f, and f2 respectively are applied to it. In the present invention the frequency multiplier 120 receives the fundamental frequencyf,, and the signal from the antenna nf. + Af and so produces a plurality of frequency components af. t b(nf. + Af). One of these components is the Doppler shift frequency Af.
The circuit that takes out a low frequency compo nents attenuates high frequencies so that only the frequency component Af is passed to the output.
Thus the Doppler shift frequency Af has been obtained directly.
The fundamental frequency fo of the signal may 130 be, for example, set at 12 GHz, and the 24 GHz transmitting wave output, when the input power of the mixer diode is 0.5 mW and the load resistance is 1 kil, is approximately 10 gW. Fine adjustment of the transmitting power can be made, by adjusting the driving power of the mixer or the bias voltage of the Gunn diode 2, or by adjusting the resistance of the load resistor 21. Accurate adjustment of the transmitting power depends upon the selection of the ordern of the harmonic signal required, during the design of the radar system, and reduction of the transmitting power is facilitated by utilizing a highorder high frequency.
However, when the ordern of the harmonic signal is large, the receiving conversion loss of the harmonic mixer increases. Therefore, it is preferable that the ordern of the harmonic signal is in the range n = 2 to 5.
A Doppler radar system according to the present invention utilizes the conversion loss of the multip lier for reduction of the transmitting power from the mixer driving power, and theref ' ore the variation of the transmitting power with time is much smaller than the fluctuation of the leakage power in a con- ventional balanced mixer system employing the same frequency for transmission.
In the Doppler radar system according to the present invention, the oscillation frequency may be made low relative to the intended frequency of transmission. In general, an oscillator device of low frequency is easier to manufacture and more stable in operation than one of high frequency.
Therefore, a millimetre wave Doppler radar system may be constructed by employing an inexpen- sive microwave oscillator device, so that the system does not require an expensive millimetre wave oscillator device or a varactor diode for multiplication.
In addition, according to the present invention, a microwave or millimetre wave Doppler radar system of high frequency may be constructed by employing an inexpensive transistor, with a low frequency band, as the oscillator device.
Referring nowto the second embodiment shown in Fig. 2, a Gunn diode 2 generating the oscillation signal also carries out multiplication for transmission and harmonic mixing for reception, thereby replacing the mixer diode. The remaining circuit elements are the same as in the first embodiment shown in Fig. 1 and are indicated by the same refer- ence numerals.
The harmonic frequency signals n -fooftheGunn diode 2, which operates at a fundamental frequency f. determined by the connection line resonator 6, are transmitted from the output waveguide 14. Reflected waves are applied directly to the Gunn diode 2, and a Doppler signal detected by nonlinear operation of the Gunn diode 2 is'produced across the load resistor 21. The load resistor 21 preferably has a resistance which is low in comparison with the DC resis- tance of the Gunn diode 2 and a value of approximately 1 M may be used. A capacitor 22 has a capacitance of at least 100 /iF in order to make the impedance low for a Doppler signal of low frequency.
Thus a Doppler radar system of low transmission 3 1 GB 2 042 300 A 3 power, when compared with the mixer driving power, can be constructed with a simple circuit structure, and it is easy to stabilize the transmission output.
Such a Doppler radar system has its oscillation frequency related to the output frequency by an integral multiple. Therefore, the coupling between the output circuit and the oscillator is low, and the oscillator is stable against external signals or load
Claims (6)
1. A short range Doppler radar system comprising:
an oscillator which generates a first signal at a first frequency; a frequency multiplier device driven by said first signal which generates a second signal, said second signal having components which are harmonics of said first frequency; a filter which selects one of said components; an antenna which radiates electromagnetic radiation corresponding to said selected component externally of the radar system, receives reflected electromagnetic radiation, produces a third signal corresponding to said reflected electromagnetic radiation and applies the third signal to the frequency multiplier; and a circuit for taking out a low frequency component from the frequency multiplier.
2. A short-range Doppler radar system according to claim 1, wherein a dielectric substrate, which carries an integrated circuit including said frequency multiplier device and a strip for coupling the output of said oscillator to said frequency multiplier device, is mounted on an inner wall of a metal package, and said filter is formed by a window provided in the package wall and a waveguide for coupling said window to said antenna.
3. A short-range Doppler radar system according to claim 1 or 2, wherein said frequency multiplier device is a mixer diode.
4. A short-range Doppler radar system according to claim 1 or 2, wherein said oscillator and said frequency multiplier device are formed by a Gunn diode.
5. A short-range Doppler radar system according to any one of the preceding claims, wherein the order of said one harmonic is at least 2 and not greater than 5.
6. A short-range Doppler radar system substantially as herein described with reference to Fig. 1 or Fig. 2 of the accompanying drawings.
Printed for Her Majesty's Stationery Office by The Tweeddale Press Ltd., Berwick-upon-Tweed, 1980. Published atthe Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP487479A JPS5598380A (en) | 1979-01-22 | 1979-01-22 | Doppler radar for short distance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2042300A true GB2042300A (en) | 1980-09-17 |
| GB2042300B GB2042300B (en) | 1983-03-09 |
Family
ID=11595808
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8002057A Expired GB2042300B (en) | 1979-01-22 | 1980-01-22 | Short-range doppler radar system |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US4319244A (en) |
| JP (1) | JPS5598380A (en) |
| DE (1) | DE3002045A1 (en) |
| GB (1) | GB2042300B (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1982002776A1 (en) * | 1981-02-06 | 1982-08-19 | Hosking Michael William | Radar sensing system |
| WO1983003309A1 (en) * | 1982-03-12 | 1983-09-29 | Simpson, Ian | Doppler radar area monitor |
| WO1983003308A1 (en) * | 1982-03-12 | 1983-09-29 | Simpson, Ian | Doppler radar area monitor |
| GB2153179A (en) * | 1984-01-18 | 1985-08-14 | Amedeo Carcassi | Doppler movement detection |
| EP0587454A3 (en) * | 1992-09-11 | 1995-02-15 | Honda Motor Co Ltd | High-frequency signal generator and radar module. |
| EP0699923A1 (en) * | 1994-08-08 | 1996-03-06 | Siemens Aktiengesellschaft | Radar apparatus |
| EP0634667A3 (en) * | 1993-07-13 | 1996-10-02 | Deutsche Aerospace | Small monopulse radar. |
| US5717400A (en) * | 1992-09-11 | 1998-02-10 | Honda Giken Kogyo Kabushiki Kaisha | High-frequency signal generator and radar module |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3322304A1 (en) * | 1983-06-21 | 1985-01-03 | Siemens AG, 1000 Berlin und 8000 München | STRIP LINE DOPPLER RADAR |
| FR2623912B1 (en) * | 1987-11-27 | 1990-03-23 | Lacroix E Tous Artifices | RADIOALTIMETRIC DETECTOR AND PROXIMITY ROCKET EQUIPPED WITH SUCH A DETECTOR |
| JP2779559B2 (en) * | 1991-09-04 | 1998-07-23 | 本田技研工業株式会社 | Radar equipment |
| US5264854A (en) * | 1992-03-12 | 1993-11-23 | Spiess Newton E | Multiple vehicle identification and classification system |
| JP3302849B2 (en) * | 1994-11-28 | 2002-07-15 | 本田技研工業株式会社 | Automotive radar module |
| US5784021A (en) * | 1996-01-25 | 1998-07-21 | Cobra Electronics Corporation | Noiseless radar detector |
| RU2132073C1 (en) * | 1997-09-19 | 1999-06-20 | Ратников Александр Юрьевич | Vehicle speed measurement technique |
| JP4005703B2 (en) * | 1998-07-09 | 2007-11-14 | 三井造船株式会社 | Array antenna transmission / reception method and frequency multiplication type millimeter-wave two-dimensional video apparatus |
| US6191724B1 (en) | 1999-01-28 | 2001-02-20 | Mcewan Thomas E. | Short pulse microwave transceiver |
| US6414627B1 (en) | 1999-10-12 | 2002-07-02 | Mcewan Technologies, Llc | Homodyne swept-range radar |
| GB0106581D0 (en) * | 2001-03-16 | 2001-05-09 | Marconi Applied Techn Ltd | Microwave oscillator |
| DE10235338A1 (en) * | 2002-08-02 | 2004-02-12 | Robert Bosch Gmbh | Sender receiver for electromagnetic radiation especially microwaves for adaptive cruise control has diode between oscillator and antenna |
| EP3351910A3 (en) * | 2008-10-29 | 2018-09-05 | VEGA Grieshaber KG | High frequency module for measuring fill levels in the w band |
| CN102495397A (en) * | 2011-12-12 | 2012-06-13 | 澳微特通信科技（西安）有限责任公司 | Waveguide excitation detector |
| US10716488B2 (en) * | 2013-12-30 | 2020-07-21 | The University Of Manitoba | Imaging using gated elements |
| DE102016101595A1 (en) | 2016-01-29 | 2017-08-03 | Infineon Technologies Ag | Methods and devices for speed and / or position detection |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4217585A (en) * | 1978-11-09 | 1980-08-12 | The United States Of America As Represented By The Secretary Of The Army | Dual frequency Doppler radar |
-
1979
- 1979-01-22 JP JP487479A patent/JPS5598380A/en active Pending
-
1980
- 1980-01-17 US US06/112,744 patent/US4319244A/en not_active Expired - Lifetime
- 1980-01-21 DE DE19803002045 patent/DE3002045A1/en not_active Withdrawn
- 1980-01-22 GB GB8002057A patent/GB2042300B/en not_active Expired
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1982002776A1 (en) * | 1981-02-06 | 1982-08-19 | Hosking Michael William | Radar sensing system |
| WO1983003309A1 (en) * | 1982-03-12 | 1983-09-29 | Simpson, Ian | Doppler radar area monitor |
| WO1983003308A1 (en) * | 1982-03-12 | 1983-09-29 | Simpson, Ian | Doppler radar area monitor |
| GB2153179A (en) * | 1984-01-18 | 1985-08-14 | Amedeo Carcassi | Doppler movement detection |
| EP0587454A3 (en) * | 1992-09-11 | 1995-02-15 | Honda Motor Co Ltd | High-frequency signal generator and radar module. |
| US5717400A (en) * | 1992-09-11 | 1998-02-10 | Honda Giken Kogyo Kabushiki Kaisha | High-frequency signal generator and radar module |
| EP0634667A3 (en) * | 1993-07-13 | 1996-10-02 | Deutsche Aerospace | Small monopulse radar. |
| EP0699923A1 (en) * | 1994-08-08 | 1996-03-06 | Siemens Aktiengesellschaft | Radar apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5598380A (en) | 1980-07-26 |
| GB2042300B (en) | 1983-03-09 |
| DE3002045A1 (en) | 1980-07-24 |
| US4319244A (en) | 1982-03-09 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19990122 |